gaumann



BAUIVIANN.

STEAM TURBINE,

APPLICATION FILED AUG.24.1917.

Patented Apr. 19, 1921.

2 SHEETS-SHEET l \NVENTOR K. BAUMANN.

STEAM TURBINE.

APPLICATION FILED AUG.24, I917.

Patented Apr. 19, 1921.

2 SHEETS-SHEET 2 I INVE NTO R MJJW'MM UNITED STATES FATE '1 rina.

KARL BAUMANN, OF URMSTON, ENGLAND, AEBSIG-BTOR T9 THE BR SH WESTING-HOUSE ELECTRIC AND IvIANUFAGTUBING CGIQIEPANY, LIMITED, A COMPANYORGANIZED UNDER THE LAWS OF GREAT BRITAIN.

STEAM-TURBINE.

Application filed August 24, 1917.

To all whom it may concern:

Be it known that I, KARL BAUMANN, a citizen of the Confederation ofSwitzerland, and a resident of Urmston, in the county of Lancaster,England, have invented a new and useful Improvement in or Relating toSteam-Turbines, of which the following is a specification.

This invention relates to steam turbines of the axial flow type.

As in a, steam turbine of this type the peripheral velocity of thoseparts of the moving blades which are nearer the shaft is less than thatof the parts near the outer ends of the blades, the velocity of thesteam leaving the inner portions of the blades 2'. 6. those portionsnearer the turbine shaft is greater than that of the steam leaving theouter portions of the blades. It is, however, desirable that the wholeof the steam leaving the moving blades should be at approximately thesame velocity when it enters the exhaust casing.

This is accomplished, according to the present invention, by providingguide blades, nozzles, velocity converting passages or the like forpartly reconverting into pressure energy the velocity energy of thewhole or part of the steam passing from the moving blades to theexhaust, so designed that the steam from every part of the bladingenters the exhaust at substantially the same velocity.

Where the turbine has only a single row of moving blades from which thesteam passes to the exhaust such guide blades, nozzles or the like areso designed as to provide passages which diverge to a greater extent ina radial direction as they approach the turbine sha t.

In the case of a turbine in which the steam passes from a plurality ofrows of moving blades to the exhaust it will be found that the leavingvelocity of the steam passing from a row of moving blades near the highpressure end of the turbine is usually greater than that of the steampassing from a row of moving blades nearer the exhaust end of theturbine. Guide blades, nozzles or velocity converting passages aretherefore provided through which the steam leaving some or all of thevrows of moving blades is caused to pass on its way to the Specificationof Letters Patent.

Patented Apr. 19, 1921.

Serial No. 187,962.

exhaust and in which the remaining velocity energy ofthe steam is partlyreconverted into pressure energy to such an extent that the steamleaving all the rows of blades will be at approximately the samevelocity when it enters the exhaust casing.

It will sometimes be found suflicient to provide such velocityconverting passages for the steam leaving only the row or rows of movingblades nearest the high pressure end of the turbine. Diverging passagesmay also advantageously be provided for the steam leaving the final rowof moving blades similar to those hereinabove described for a turbine inwhich the steam passes from a single row only of moving blades to theexhaust.

In the accompanying drawings Figure 1 is a longitudinal section of aturbine of the axial flow steam type with one form of guide ladesforming diverging passages for partly reconverting into pressure energythe velocity energy of the steam before it enters the exhaust casingconstructed in accordance with the present invention, Figs. 2 and 3 being sections taken respectively on the lines II-II and II-IIII ofFig. 1. Fig 4 illustrates a turbine provided with means constructed inaccordance with the present invention for partly reconverting thevelocity energy of the steam leaving an inner portion only of the finalrow of moving blades, Fig. 5 being a section taken on the line V--V ofFig. 4.

In Fig. 1 the steam passes to the exhaust casing 6 from the outerportions of the rows of moving blades 7, 8 and 9 and from the whole ofthe final row of moving blades 10. A row of fixed guide blades 11 islocated opposite the outer portion of the row of moving blades 7 which,as shown in Fig. 2, form between them diverging passages through whichthe steam leaving the outer portion of said row of moving blades 7passes on its way to the exhaust casing 6. Said row of fixed blades 11are inclosed at their outer ends by a shrouding or wall 12 which mayconveniently be formed in conjunction with the shrouding or wall 13 forthe fixed guide blades preceding the outer ends of the moving blades 8.The passages between the blades 11 also diverge in a radial direction.Similar fixed. guide blades 14;

mounted on the shrouding 15 for the fixed guide blades preceding theouter ends of the moving blades 9 and inclosed by a shrouding 16 arealso provided in connection with the outer portion of the row of movingblades 8 to form, as shown in Fig. 3, diverging passages through whichthe steam leaving said outer portion of the blades 8 passes beforereaching the-exhaust casing 6.

Similar fixed guide blades may a-so be provided for the steam leavingthe outer portion of the row of moving blades but as the leavingvelocity of the steam passing from the rows of moving blades 7 and 8 isusually greater than that of the steam passing from the moving blades 9and 10, the provision of diverging passages for the steam leaving therows of moving blades 7 and 8 will usually be found suiiicient to insurethat the steam leaving all the rows of moving blades 7, 8, 9 and 10 willbe at approximately the same velocity when it enters the exhaust casing6.

In Figs. 4: and 5 a row of fixed guide blades 17 is provided supportedon adrum 18 attached to the exhaust casing 6 and in closed by acircumferential wall or shrouding 19. In this construction the fixedblades 17 are of such a height that only the steam leaving the innerportion of the final row of moving blades 20 passes through thediverging passages formed between the fixed blades 17 and the drum 18and shrouding 19. As the peripheral velocity of the inner portion of theinner row of moving blades 20 is less than that of the outer portionoi": said row of blades the velocitv of the steam leaving the innerportion of said blades is higher than that leaving the outer portionthereof. The higher velocity energy of the steam l aving the innerportion of the moving blades 20 will be partly reconverted into pressureenergy by the diverging passages formed as aforesaid, with the resultthat the steam leaving the outer portion of the row of blades 20 andthat leaving the fixed blades 17 will be at approximately the samevelocity on entering the exhaust casing 6. The absolute pressureimmediately behind the moving blades 20 will be lower in the innerportion than in the outer portion, and in order to prevent leakage andother losses it is advisable to separate the inner tier from the outertier of the moving blades by dividing lugs 21, and to provide dummystrips 22 to obtain a small clearance between the lugs and the wall 19.

Diverging passages constructed as describedwith reference to Figs. 4 and5 may advantageously be employed not only in turbines having one rowonly of moving blades from which the steam passes to the exhaust butalso in connection with the final row of moving blades of turbines inwhich the steam passes to the exhaust from a plurality of rows of movingblades as illustrated for example in Fig. 1 of the accompanvingdrawings.

By adding the above described row or rows of guide blades, nozzles, ordiverging passages the leaving energy in the exhaust steam will bepartly reconverted into pressure immediately after leaving a row or rowsof moving exhaust blades and before the steam enters the exhaust casingor passages, thus-increasing the erficiency of the turbine.

The invention is not limited to the constructional forms hereindescribed and illustrated which have been given by way of example onlyas the diverging passages may be formed in various other ways lyingwithin the scope of the invention as hereinafter definel by the appendedclaims.

I am aware that it is not broadly new to provide means for partiallyreconverting into pressure energy the velocity energy of the steampassing from the blading of a turbine to the exhaust and I make no suchclaim.

I claim as my invention:

1. Inan axial flow steam turbine, a steam receiving chamber adapted toreceive the steam passing through the turbine stages upon a plurality ofannular, deflecting surfaces, the angle of deflection of each surfacevarying proportionally with the velocity of the steamreceived thereupon.

2. In an axial flow steam turbine, a plurality of vanes and passagesformed in the turbine casing for the steam leaving difi'ercnt annularportions of said vanes, adapted to convert the respective velocityenergy of the'steam from each of said portions into. a standard velocityenergy.

3. In an axial fiow steam turbine having an exhaust chamber and a movingrow of blades adapted to discharge thereinto means for converting thevelocity energy of the steam leaving a portion of said blades into avelocity energy equal to that of the steam leaving another portion ofsaid blades.

4. In an axial flow steam turbine having an exhaust chamber and a finalrow of moving blades conversion devices arranged to receive the steamissuing from the inner porlions of said blades and adapted to convertsome of its velocity energy into pressure energy so that the velocity ofthe steam issuing from said devices will be substantially the same asthe velocity of the steam leaving the outer ends of said blades.

In. an axial flow steam turbine; an ex haust' chamber and a final row ofblades and conversion devices carried within said exhaust chamber andpositioned to receive the steam issuing from those portions of saidblades nearest the turbine shaft; said conversion devices beingproportioned so as to convert sufficient of the velocityienergy of thesteam passing therethrough into pressure energy so that the velocityenergy of the steam issuing therefrom will be substantiallv equal to thevelocity energy of the steam leaving the outer ends of said blades.

6. In an axial flow steam turbine, vanes, a steam receiving chamberadjacent said vanes and annular guides in said chamber arrangedconcentrically with the axis of the turbine and with their surfacesinclined 1 with respect to said axis, the angle of in clination of therespective guides decreasing from said axis to the circumference of saidchamber.

In testimony whereof I have hereunto subscribed my name this tenth dayof July, 5

KARL BAUMANN. Witnesses WILFRED MORRIS, F REDERIOK NIXON.

